The present invention relates to an axle assembly having a fixed axle housing and a rotating axle body rotatably mounted in the housing.
Agricultural vehicles are often provided with systems for regulating tire pressure, so that tire pressure can be controlled during operation of the vehicle to reduce tire pressure to reduce ground impact, and to increase tire pressure for street travel. This also enables adjustment of the tire pressure to various load situations. Agricultural vehicle tires can be inflated by feeding pressurized air to the wheels via a system of passages in the axle assembly.
U.S. Pat. No. 6,439,044 discloses a tire pressure regulation apparatus having a rotary pressure transmitting assembly for transmitting pressure to a rotating wheel from a non-rotating fixed part of the vehicle. This assembly includes a rotating annular member and a non-rotating annular member, both concentric to the axis of rotation. The annular members are coupled together by guide bands. The annular members are spaced apart axially from each other on opposite sides of a movement gap. Concentric annular grooves are formed in a surface of the non-rotating annular member which faces the rotating annular member. A pair of ring seals are mounted in each groove. The ends of the grooves opposite from the rotating annular member are connected to a pressurized control line. When a control pressure is applied to the grooves, the seals are moved toward the rotating annular member, thus sealing around a passage which opens into a chamber.
A drawback of this pressure regulation apparatus is that there is high wear between the annular members and the guide bands due to the constant relative movement between the annular members and the guide bands. Additionally, this apparatus provides only a small pressure flow passage, resulting in flow rates and long tire filling times. Longer filling times produce more frictional wear, resulting in more frequent maintenance. Moreover, the annular grooves are costly to manufacture.